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  • 1
    Electronic Resource
    Electronic Resource
    The relationship between decrease in Cx32 and induction of P450 isozymes in the early phase of clofibrate hepatocarcinogenesis in the rat (1999)
    Springer
    Archives of toxicology 73 (1999), S. 373-380 
    Details
    ISSN: 1432-0738
    Keywords: Key words Clofibrate ; Connexin ; Liver ; Promotion ; P450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To examine the relationship between the decrease in connexin 32 (Cx32) and induction of P450 isozymes in the early phase of clofibrate hepatocarcinogenesis, a total of 20 male F344 rats were initiated with a single intraperitoneal injection of 150 mg/kg of diethylnitrosamine (DEN) or given the saline vehicle alone and starting 2 weeks later given diet containing 0.18, 0.09, and 0% clofibrate for 6 weeks. All animals were subjected to two-thirds partial hepatectomy at week 3 and killed at week 8. Absolute and relative (ratios to body weight) liver weights were significantly increased in the DEN + clofibrate groups compared with the DEN-alone group. Diffuse hepatocellular hypertrophy with granular cytoplasmic eosinophilia characterized by a marked increase in peroxisomes and smooth endoplasmic reticulum, was observed in the clofibrate treated rats. Induction of cytochrome P450 (CYP) 4A1 and 2B1/2 was noted in the DEN + clofibrate groups, this being most marked in the CYP 2B1 case. Immunohistochemically, positive immunostaining for anti-CYP 4A1 and CYP 2B1 were observed diffusely and centrilobularly, respectively. The numbers and areas of Cx32-positive spots per hepatocyte in the centrilobular areas in the treated rats were significantly decreased in an essentially dose-dependent manner, but no changes were observed in periportal areas. The numbers and areas of foci positive for glutathione S-transferase placental form (GST-P) were decreased in a dose dependent manner in the clofibrate treated groups. These results suggest that the CYP 2B1/2 induction and Cx32 decrease in centrilobular hepatocytes, similarly to those thought to be involved in the hepatic promotion mechanism of phenobarbital, may also play important roles in clofibrate actions in the liver, in addition to its causation of oxidative DNA injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050676
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  • 2
    Electronic Resource
    Electronic Resource
    Comparative studies of the toxicity of standard reference materials in various cytotoxicity tests and in vivo implantation tests (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 4 (1993), S. 153-156 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyurethane films that contained various amounts of zinc diethyldithiocarbamate (ZDEC) and zinc dibutyldithiocarbamate (ZDBC) were prepared as standard reference materials (SRM). Using three cell lines of V79, L929, and Balb/3T3 cells, the cytotoxicity of the dithiocarbamates and the SRM films were compared by agar diffusion assay, filter diffusion assay, neutral red assay, cell growth assay, and colony assay. Among these in vitro cytotoxicity tests, colony assay was found to be the most sensitive method for detecting the cytotoxicity. The cytotoxic potentials of extracts from SRM films correlated well with the concentrations of ZDEC or ZDBC involved in SRM. When various rubber materials including SRM and surgical rubber latex materials were tested, cytotoxic potentials of these extracts were also correlated with the inflammatory tissue capsule thickness in short-term implantation tests. On the basis of these results, the SRM is judged to be useful for validating test sensitivity, and comparing the correlation between in vitro and in vivo responses. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770040206
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  • 3
    Electronic Resource
    Electronic Resource
    Rabbit eye irritation caused by wearing toxic contact lenses and their cytotoxicities: In vivo/in vitro correlation study using standard reference materials (1993)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 27 (1993), S. 885-893 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To clarify the relationship between eye irritancy and cytotoxic potential induced by irritant materials, we made lenses coated with standard reference materials (SRMs) prepared from various amounts of zinc diethyldithiocar-bamate (ZDEC) and polyurethane (PU).Zinc diethyldithiocarbamate was classified as a mild irritant by the Draize eye irritation test. When ZDECSRM coated contact lenses were applied to rabbit eyes, Draize scores increased in proportion to both the ZDEC and PU concentrations used for coating. Furthermore, correlation with the cytotoxic potential (γ = -0.93) was better than with lactate dehydrogenase (LDH) activities of tears from rabbit eyes wearing these coated lenses (γ = 0.78). In conclusion, in vivo eye irritancy induced by wearing lenses could be estimated quantitatively with the cytotoxic potentials using a colony assay. Further-more, we could compare different sensitivities caused by the same set of SRMs among three different sites of tissue. As a result, the order of sensitivity was eye 〉 muscle ≫ skin. © 1993 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820270707
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  • 4
    Electronic Resource
    Electronic Resource
    Comparative studies by cell culture and in vivo implantation test on the toxicity of natural rubber latex materials (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 339-356 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Colony assay using V79 cells, the agar diffusion assay with L929 cells, and the 7-day rabbit muscle implantation test were employed to evaluate the cytotoxicity and tissue toxicity of natural rubber latex (NRL) materials. The in vivo implantation test showed that, among 13 histological parameters, thickness of inflammatory layer was the most useful index to evaluate tissue responses quantitatively. A comparison of the in vivo and in nitro parameters revealed the following correlations between the thickness of the inflammatory layer and cytotoxicity indices: Colony assay of the extracts, IC50: r = 0.80; Agar diffusion assay, Zone index: r = 0.73; Lysis index: r = 0.61. From these results, it appears that the colony assay provides a more reliable prediction of the tissue response than the agar diffusion assay.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260306
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    Paper (German National Licenses)
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